Distributed network systems have been widely adopted with the emergence of the cloud for computing applications. Network systems encompass numerous connected devices including servers, switches, and other components that exchange data. Connections between such devices have generally been wired connections in the past, but with the demand for speed and increased amounts of data, faster optical signal cables have been used. For example, recent transmission speeds in optical systems exceed 10 Gbps and reach 100 Gbps, thus addressing the need for increased data capability and speed.
Optical signals are sent and received through transmitters that include electronics that are necessary to relay optical signals. An optical transceiver transmits and receives optical signals through an optical connector mated by optically active devices of a light-emitting device and a light-receiving device, each made of semiconductor materials. An optical transceiver includes electronic components and an optical receptacle that receives the optical connector. One type of optical transceiver is a plug in optical transceiver. Such an optical transceiver is inserted into or removed from a transceiver cage provided on a printed circuit board in an optical switch device. The transceiver engages an electrical plug with an optical connector in the cage. The use of optical transceivers results in relatively more power consumption, and therefore heat generation by the electronic and optical devices in the optical transceiver. An effective heat-dissipating mechanism is thus required.
FIG. 1 shows an optical switch 10 for optical transceivers that includes a number of transceiver cages 12 mounted on the front side of a housing 14. The transceivers 12 each may receive optical transceivers for connection of optical signals to the optical switch 10. The transceivers are inserted into or removed from a front opening on one of the cages 12. The rear end of the transceiver has an electrical plug. The transceiver can electrically communicate with the host system on the optical switch 10 by engaging this plug with an optical connector provided on the opposite end of the cage. A series of heat sinks 16 is provided on top of the cages 12 to dissipate heat generated from the transceivers. A clip 18 binds the heat sink 16 with the cages 12.
The cage design allows the transceiver to contact the heat sink 16 and thereby remove heat generated by the transceiver. In such a cage design, the heat sink 16 is mounted over the transceiver, and thus the bottom of the heat sink 16 contacts the inserted transceiver to dissipate the heat. The heat sink 16 is designed with a bevel on the bottom side that faces the inserted transceiver. Thus, when transceiver is inserted into the cage 12, the transceiver contacts the bevel and lifts the heat sink 16, creating contact with the heat sink 16. Although the heat sink 16 has the clip 18 to produce a contact force between heat sink 16 and transceiver, the contact with the transceiver often has an inadequate contact surface. For example, roughness of the top surface of the transceiver and the beveled contact surface on the heat sink 16 affects the heat-transfer efficiency. Also, although both the contact surface of the transceiver and the heat sink 16 are metal objects, the contact surfaces between them are not smooth and therefore gaps exist on the surface. The gaps result in only a few points that function as contacts, which causes the heat conduction to have relatively low efficiency. For increasing the contact surface between the transceiver and heat sink 16, a thermal interface material may be used on the contact surface of the transceiver to improve the thermal contact resistance with the heat sink. However, in this design, when the transceiver is inserted into the cage, the shear force from the contact between the transceiver and the heat sink 16 may damage the thermal interface material.
Thus, there is a need for a heat sink configuration that allows better airflow to transfer heat away from an optical transceiver inserted in a transceiver cage. There is also a need for a transceiver cage configuration that allows maximum contact between a transceiver and a heat sink. There is also a need for a transceiver cage configuration that prevents shear damage from repeated insertion and removal of the transceiver from the transceiver cage.